CREB is inactivated in SN dopaminergic neurons of PD patients. A, B, Sections of human SN obtained from control or PD individuals were immunostained using the p-CREB (A) or CREB antibody (B), respectively, and visualized by DAB staining. Boxed areas are shown at higher magnification in the images below. Scale bars: low magnification, 100 μm; high magnification, 20 μm. C, Adjacent sections of human SN from control or PD individuals were immunostained using the p-CREB or NURR1 antibody, respectively, and visualized by DAB staining. Representative images of p-CREB (top) and NURR1 (bottom) from the same dopaminergic neuron. Scale bar, 20 μm. D, Analysis of the correlation between p-CREB and NURR1 expression in control (n = 3, 133 dopaminergic neurons) and PD (n = 3, 60 dopaminergic neurons) individuals. Pearson correlation coefficient r = 0.4306, p < 0.0001.